diff --git a/woa/init.py b/woa/init.py
index c52be12..4c50969 100644
--- a/woa/init.py
+++ b/woa/init.py
@@ -1,4 +1,5 @@
 import asyncio
+import os
 import time
 from aiohttp import web, ClientSession, FormData, ClientTimeout
 from wechatpy.crypto import WeChatCrypto